A Canadian study shows that HPV shots don't make girls promiscuous, as some parents have feared. But given that HPV causes about 70% of cervical cancers, this is hardly something we should be worrying about.

The human papilloma virus (HPV) is a serious health problem. It's the most common STD in America and, with the exception of HIV, the most fatal. It's known to cause several types of cancer, including carcinomas of the cervix, anus, penis, and throat. It's imperative, therefore, that we encourage HPV vaccinations for both girls and boys.

The new study, which now appears in the Canadian Medical Association Journal, tracked more than 260,000 girls, of which half were eligible to receive HPV shots when Ontario introduced a vaccination program to Grade 8 students in 2007 and 2008. The researchers examined data on vaccine receipt and indicators of sexual behaviour, specifically pregnancy and non-HPV-related STDs.

HPV vaccination and eligibility for the program did not increase the risk of pregnancy or the STIs among females aged 14 to 17, the researchers found.

"We present strong evidence that HPV vaccination does not have any significant effect on clinical indicators of sexual behaviour among adolescent girls," the study's authors conclude in Monday's CMAJ issue.

"These results suggest that concerns over increased promiscuity following HPV vaccination are unwarranted and should not deter from vaccinating at a young age."

They found nearly six per cent of the girls, who were followed over about four years, become pregnant or contracted a sexually transmitted infection (STI). Overall, 10,187 pregnancies and 6,259 cases of STIs were documented. [emphasis added]

This is the largest study on the association between the HPV vaccination and its links to sexual behavior.